Chemical vapour transport of ternary cobaltmolybdates - Experiments and model calculations

The chemical vapour transport behaviour of the phases in the Co/Mo/O system has been investigated using Cl-2 and Br-2 as transport agents in a temperature gradient 1173 to 1073 K. Single crystals Of Co2Mo3O8, CoO, Co3O4 and Co have been obtained, whereas the deposited CoMoO4 crystals are destroyed during cooling down to room temperature due to a phase transition at about 660 K. Pure powders of the ternary compounds have been used as starting materials as well as mixtures of three coexisting phases. The observed transport behaviour is compared with results of thermodynamical model calculations. The influence of source composition, transport agent and the moisture contents is described in detail.

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